objective c-AVPlayer控制音量播放

AVPlayer控制音量播放

開發一個自定義播放，用到AVPlayer類，現在想加入UISlider控制音量。

實現代碼：

NSMutableArray *allAudioParams = [NSMutableArray array];
AVMutableAudioMixInputParameters *audioInputParams =[AVMutableAudioMixInputParameters audioMixInputParameters];
[audioInputParams setVolume:volumeSlider.value atTime:kCMTimeZero];
[allAudioParams addObject:audioInputParams];
AVMutableAudioMix *audioZeroMix = [AVMutableAudioMix audioMix];
[audioZeroMix setInputParameters:allAudioParams];
[self.playerItem setAudioMix:audioZeroMix];

步驟地為什麼不好使。請大家幫忙，謝謝。

最佳回答：

NSArray *audioTracks = [asset tracksWithMediaType:AVMediaTypeAudio];

NSMutableArray *allAudioParams = [NSMutableArray array];
for (AVAssetTrack *track in audioTracks) {
  AVMutableAudioMixInputParameters *audioInputParams = 
    [AVMutableAudioMixInputParameters audioMixInputParameters];
  [audioInputParams setVolume:volume atTime:kCMTimeZero];
  [audioInputParams setTrackID:[track trackID]];
  [allAudioParams addObject:audioInputParams];
}

AVMutableAudioMix *audioMix = [AVMutableAudioMix audioMix];
[audioMix setInputParameters:allAudioParams];

[playerItem setAudioMix:audioMix];

用這段代碼控制音量